Some wireless and wired communications services downed by Hurricane Sandy have been restored over the past 24 hours, but FCC officials said Wednesday afternoon that several serious outages remain in New York, New Jersey and some other hard hit areas.

Meanwhile, AT&T and T-Mobile announced that they are jointly taking the extraordinary step of allowing roaming over both of their wireless networks in the storm-torn areas.

The agreement means that a customer will see no increase in a cellular bill if wireless voice or data calls are re-routed to the carrier that's not his or her own. The carriers expect that the agreement will allow more calls to connect.

"The crisis is not over," FCC Chairman Julius Genachowski said in a statement issued at 3:45 p.m. ET today following a conference call with reporters. "This was and remains a devastating storm."

Genachowski praised the first responders to areas hit by the storm and offered condolences to the families who lost loved ones.

Federal Communications Commission Public Safety Chief David Turetsky said that about 22% of cell sites on towers and buildings in 158 counties in 10 states hit by the storm were out of service as of 10 a.m. ET Wednesday, down from 25% that were out-of-service 24 hours earlier.

Turetsky said 911 calls are reaching emergency call centers, though some are being re-routed. He did note that some 911 calls are arriving at call centers without location information.

Many cell sites are running on backup power, and the carriers are installing portable generators in some locations to improve service, Turetsky added.

Broadband and cable services to homes and businesses, including telephone and TV and Internet, have improved as well, with fewer than 20% of locations in the affected areas still without service, down from 25% yesterday, Turetsky said.

He said a "small number" of radio stations were still offline, but didn't elaborate.

"The data is not uniform across all counties," he said, noting greater damage to communications from flooding, debris and high winds in New York and New Jersey especially. In those areas, improvement may take longer than in some other locations.

Earlier Wednesday, Verizon officials called the situation in lower Manhattan "bleak" due to flooding and power outages affecting wired and wireless communications.

Verizon said it has erected a temporary wireless antenna in Jersey City across the Hudson River from the World Trade Center to support major financial organizations in northern New Jersey.

Turetsky commended AT&T and T-Mobile for allowing roaming between the networks. Both carriers use network technology based on GSM and UMTS standards, which makes the sharing possible.